[Java] ArrayDeque

ArrayDeque is implemented by array. When capacity increased, it will create a new array and copy the old one to new.

import java.util.*;
import java.lang.reflect.*;

public class ArrayDequePerformance {
  public static void main(String[] args) {
    try {
      long s1 = now();
      ArrayDeque<Integer> q = new ArrayDeque<>();
      for (int i = 0; i < 16777215; ++i) {
        q.add(1);
      }
      long e1 = now();
      System.out.println(e1 - s1);

      Field f = q.getClass().getDeclaredField("elements");
      f.setAccessible (true);
      Object[] ar = (Object[])f.get(q);
      System.out.println(ar.length);

      long s2 = now();
      q.add(1);
      long e2 = now();
      System.out.println(e2 - s2);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
  public static long now() {
    return System.currentTimeMillis();
  }
}

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